The invention relates to a magnetic resonance (MR) device for MR imaging as well as to an RF coil system for such an MR device.
MR devices of this kind are generally known and described in numerous documents, for example, in U.S. Pat. No. 6,377,045 which discloses a magnetic resonance device for carrying out the SENSE method by means of an RF coil array. The optimization of RF coil arrays is of major importance for MR imaging. For given clinical protocols a specific optimization of the image quality can be achieved by parameter variation of the coil number, the coil configuration and the arrangement of the coils. The object basically consists of obtaining a maximum signal-to-noise ratio (SNR). A high SNR in deeper layers is achieved by means of RF coils having a given minimum size. However, the maximum number of RF coils in relation to the given size of the object to be examined, for example, a patient, is thus limited. When using parallel imaging methods, such as SENSE or SMASH the number of RF coils is increased so as to obtain a high reduction factor for a corresponding temporal resolution.
It can be stated in principle that the design criteria for RF coils differ significantly in dependence on the relevant application and the imaging method. For example, when the SENSE imaging method is used, a low error propagation rate should be achieved in combination with a high reduction factor, whereas maximization of the SNR is most important when synergy coils are used. It follows therefrom that an RF coil array which has been optimized for the SENSE method also deviates geometrically from a synergy coil array in respect of the number, the size and the position of the RF coils.
For clinical applications it is desirable that switching over between and selection of different applications and imaging methods can take place at will without it being necessary to move the patient in order to fit a new RF coil array. Therefore, it is an object of the invention to provide an MR device as well as an RF coil system for such an MR device which enable such selection and switching.